cloudy water

Causes and cures for cloudy swimming pool water.
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cloudy water

Postby DD » Fri 13 Jul, 2007 14:19

Been reading these forums this morning after a week of cloudy water and I think I have come to the right place. Just came from the pool store heres what I have.

18' round above ground
200 lb sand filter

saturation index -.30
Total Dissolved solids 0
FC .1
TC .6
CC .5
pH 7.5
CA 9
copper 0
Iron 0
Total Alkal 111
Calcium Hard 143

1. I have trying the suggestion earlier of vacuuming the pool to waste
2. I just shocked it and added some stabilized chlorine also

I know my chlorine levels are low. I think I am on the right track here. Any suggestions to on what to keep a eye on in the future so I dont run into problems every year? It seems I always have a problem wi8th my pool on a yearly basis.

I noticed this morning a foam and some stringy material in the foam floating. What is this? It breaks up when i touch it,

One last ? CA does UV sheild raise this and why is it important?

Ty in advance im kinda lost here.


sorry for repost

Postby DD » Fri 13 Jul, 2007 14:20

Also I tried to register and received a error when I tried validating my passy.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Postby chem geek » Fri 13 Jul, 2007 16:48

Are you sure the Cyanuric Acid (CYA) level was 9? I suppose that's why they told you to use some stabilized chlorine. What kind of chlorine have you been using up to this point? If you used Trichlor pucks/tabs (or Dichlor powder), then I doubt very much that your CYA level is really 9.

Anyway, your pool is low in chlorine and is developing an algae bloom so shocking it with chlorine is the right thing to do. But to really know how much chlorine is needed, you need to accurately know your CYA number. Get yourself a good test kit, the Taylor K-2006 you can get from Taylor here or from Leslie's here or the even better test kit based on the K-2006 from tftestkits here.

Shock your pool by raising the Free Chlorine (FC) level to 40% of your CYA level and hold it there by testing and adding more chlorine as often as you can -- at least two or three times a day. Algae will consume chlorine quickly and you already will lose some during the day due to UV rays from sunlight. You want to keep the shock level of chlorine until all of the following occurs: 1) the pool is crystal clear, 2) you measure minimal drop in FC overnight (< 0.5 ppm), and 3) you measure minimal Combined Chlorine (CC) (< 0.5 ppm).

If you have a lot of dead algae that settles to the bottom of the pool and doesn't filter out (if you don't have a floor drain, for example), then you may need to vacuum to waste. You will also need to backwash your filter when the pool looks clear.

As for Cyanuric Acid (CYA or what they call CA but I prefer CYA so as not to mix it up with calcium hardness which is usually CH but some people have done CA, hence the confusion), you have to have some of it or else the chlorine will break down by the UV rays of the sun. Without CYA, half of the FC level will degrade in a half-hour in direct noontime sun. However, CYA binds with most of the FC so the resulting disinfecting chlorine is much lower. In order to prevent algae, you need to target an FC level of 11.5% of your CYA level with an absolute minimum FC of 7.5% of your CYA level. Typical CYA levels that work reasonably well are 30-50 ppm but if you are in a very sunny area you might use more, BUT then will have a harder time doing a chlorine shock since it will take that much more chlorine. Using a pool cover that is opaque to UV will save you a lot in chlorine usage.

Be aware that both Trichlor and Dichlor add CYA to the water. With Trichlor, for every 1 ppm FC you also get 0.6 ppm CYA. With Dichlor, for every 1 ppm FC you also get 0.9 ppm CYA. Also be aware that when using Cal-Hypo, you increase Calcium Hardness (CH). With every 1 ppm FC from Cal-Hypo you also get 0.7 ppm CH. Bleach and chlorinating liquid (and the expensive lithium hypochlorite) do not add any CYA or CH -- only chlorine (and salt). If you cannot add chlorine daily or do not have a pool cover (which lets you add chlorine 2-3 times per week instead) then you might be interested in The Liquidator for automatically dosing bleach or chlorinating liquid into the pool.

If you want to use Trichor because it is conveniently slow-dissolving, remember that it is also highly acidic and you must do one the following to avoid algae:

1) Increase the FC level corresponding to the CYA level (as mentioned above).

2) Dilute the pool water regularly through partial drain/refill or more frequent backwashing to keep the CYA constant.

3) Not worry about higher CYA and use some sort of algaecide such as PolyQuat 60 added on a weekly basis (or copper, but that can have side effects if not carefully balanced).


Postby DD » Mon 16 Jul, 2007 07:59

Well those numbers I gave you are from the computer print out at the store. Still lime green and cloudy today. Adding chlorine and draining/vacumming to waste still. I think I might back the truck up into it and finish ther job. Thanks for your advice I aprreciate it,.

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